Feuding relatives faced off in court yesterday at the start of a battle to gain custody of the two daughters of a Staten Island woman charged with murdering her fire marshal husband as he slept in their bed.

Relatives of Janet Redmond-Mercereau and her slain hubby, Douglas Mercereau, have exchanged harsh words in the past, and sparks had been expected to fly at the hearing in Staten Island Family Court.

But the loudest sounds in the courtroom were the muted voices of lawyers as they made requests on behalf of those seeking custody: Redmond-Mercereau’s two sisters, Joanne Scalia and Mary Anne Redmond, and Mercereau’s brother, Brian, and two of his other relatives.

The custody issue will not be decided until Judge Terrence McElrath rules on an Administration for Children’s Services complaint accusing Redmond-Mercereau of neglecting her children by slaying their father.

If the widow is found guilty of neglect, she will lose the right to be the parent of the girls, ages 5 and 6.